On Tue, Feb 21, 2006 at 10:29:35PM +0100, Stephane Bortzmeyer wrote:
Does any other persons use a test on the validity of the MX record of
the sending domain? Not just that there is a MX but also that it is
not a RFC 1918 address or a loopback address?
Postfix allows it with check_sender_mx_access and I always find it
very useful but it fails with Sourceforge:
https://sourceforge.net/tracker/index.php?func=detail&aid=1435118&group_id=1&atid=200001
However, you have to be careful with that technique these days.
Some people intentionally put RFC1918-ish A records in with
their high MX records. Figuring that a spammer, who intentionally
targets high MX records, will hit themselves.
Another idea that I've seen some use is to put a valid A record in for
their high MX values. And any mail that hits there is automatically
spam-trapped. Since the lower valued MX records should have accepted
the message. This is fine, so long as one of them *does* and you
never run into a situation where *all* of your lower MX records
are simultaneously refusing your mail.
--
/ \__ | Richard Rognlie / Sendmail Ninja / Gamerz.NET Lackey
\__/ \ | http://www.gamerz.net/~rrognlie <rrognlie at gamerz.net>
/ \__/ | Creator of pbmserv(_at_)gamerz(_dot_)net
\__/ | Helping reduce world productivity since 1994
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